>>83231One downside of the phat model for an adult is that the stylus is both shorter and thinner compared to the Lite and the 3DS, making the stylus harder to hold.
Overall, the 3DS is a decent option, but there are some downsides to using it for GBA and DS games.
One is that the position of the dpad directly below the circle pad makes the dpad uncomfortable to use for a long period of time.
Another is the screen scaling. By default the image is scaled up to fill the higher-resolution screens, which makes the image look blurry and ugly. There is a pixel-perfect option, but this makes the image appear even smaller than on the original GBA model and the original DS model because the pixels are physically smaller.
And you miss out on functionality in games that use the bottom GBA slot for anything. This includes those games where it's required like those with unique hardware attachments that you mentioned, but there are also quite a few games where the bottom slot enables bonus functionality like transferring Pokemon from Gen 3 to Gen 4, unlocking a music video in WarioWare Touched, getting rumble in Ouendan 2, instantly unlocking all the cases in the Japanese Phoenix Wright trilogy, etc.
There's also a small portion of GBA titles that currently don't function properly on a softmodded 3DS.